The Davenport Model B screw machine is one of the world's most popular machine tools. Although completed in 1927, the design of the Model B has withstood the test of time and continues to compete favorably with computer controlled machine tools introduced much more recently. Perhaps this is because the Model B is economical to purchase and use and highly reliable in operation.
The present invention comprises an improvement over the Davenport Model B. While preserving many features of the Model B, the machine tool of the present invention differs therefrom by providing a servo mechanism for operating the cam shafts and the indexing mechanism of the machine tool. The machine tool of the present invention further differentiates over the prior art by providing a variable frequency drive motor for operating the spindles of the machine tool. The machine tool of the present invention further differentiates over the prior art by providing a servo mechanism for performing threading operations. The machine tool of the present invention further differs from the prior art in that it is provided with a computer controlled system which controls and monitors the entire operation of the machine tool.
In accordance with the broader aspects of the invention, a machine tool is provided with a cam shaft and indexing drive mechanism which is independent from the spindle drive mechanism. The cam shaft and indexing drive mechanism is driven by a servomotor and is therefore adapted for operation within a wide range of operational parameters. An encoder provides feedback to the servo drive mechanism to effect operational control.
The machine tool of the present invention further comprises a variable frequency drive motor which operates the spindles of the machine tool. In this manner the rotational speed of the spindles is precisely controlled.
The machine tool of the present invention further comprises a servo-operated threading mechanism. The threading mechanism is operable at one or more workstations of the machine tool to provide threading of parts manufactured thereby.
The machine tool of the present invention further comprises a computer control system which controls and monitors the entire operation of the machine tool. In particular, the computer control system regulates the operation of the cam shaft and indexing servo mechanism, controls the operation of the threading servo mechanism, and controls the operation of the variable frequency spindle drive motor.